1. Field of the Invention
The present invention relates to a process of and a system for flouring wheat.
2. Description of the Prior Art
It has hitherto been known that a wheat flouring process comprises the step of milling wheat grains to produce a flour. Ordinarily, the wheat grains to be milled in the milling step are subjected to pretreatment. The pretreatment process includes the steps of polishing the wheat grains, humidifying the grains and subjecting the grains to a treatment usually referred to as "conditioning".
As well-known, wheat grains each includes an endosperm part which contains starch, gluten-parenchyma and an aleuron layer. The aleuron layer constitutes a surface layer of the endosperm part. The endosperm part is covered with several layers which contain an exosperm layer adjacent to the aleuron layer, a testa layer covering the exosperm layer and a layer of pericarp outside the testa layer. The grain also includes embryo. The abovementioned polishing step is performed for stripping and removing from the grains surface portions of the latter including layers of pericarp, testa, exosperm and aleuron.
The polished grains are then humidified, and thereafter subjected to the conditioning. The conditioning of the grains is performed for making the physical and chemical properties of the grains, such as moisture content of the latter, optimum for the subsequent milling operation.
It is to be noted that the term "conditioning" is used in this specification and the appended claims in a broad concept including cold conditioning usually referred to as tempering, warm conditioning, hot conditioning, stabilizer conditioning, drying operation and the like.
Wheat grains obtainable in Japan as raw material for the wheat flouring ordinarily have moisture content of 11 to 12% by weight of the grains. In a wheat flouring process, the wheat grains polished in the polishing step are humidified and then subjected to conditioning so as to increase the moisture content of the grains to the value of 15 to 16% by weight of the grains which is most suitable for the subsequent milling operation. However, when the wheat grains are humidified after they have been polished and hence surface portions of the grains have been partly stripped and removed therefrom, the humidified grains become prone to stick together into lumps of the grains due to an action of gluten and starch contained in the surface portions of the grains. When the lumps of the humidified grains are formed in a tempering tank, for example, they cannot be preferably milled into a flour in the subsequent milling operation.